More Healthcare Workers Tied to Missouri H5N1 Bird Flu Case Developed Symptoms

Four additional healthcare workers who cared for the Missouri patient confirmed to have H5N1 bird flu developed mild respiratory symptoms, CDC reported on Friday.

One of those workers was in the higher risk category because they saw the patient before droplet precautions were put in place, according to the CDC. They provided a blood sample for serology testing to determine whether they were infected with H5N1, the agency said.

The other three healthcare workers were among the 94 workers who had contact with the patient after droplet precautions were in effect, theoretically putting them at lower risk, CDC said.

Blood samples have been collected from these three workers for serology testing as well, the agency said.

A total of six healthcare workers who had contact with the H5N1 case have now reported respiratory symptoms. The first healthcare worker tested negative for influenza (though it’s still unclear whether this person will also have a blood sample collected for serology). The other five only had mild symptoms and were not tested for flu, CDC said.

Amesh Adalja, MD, of the Johns Hopkins Center for Health Security in Baltimore, previously told MedPage Today that COVID levels were high when this case was hospitalized on August 22, therefore it’s possible that all of these healthcare workers had some illness besides H5N1.

Nonetheless, if these healthcare workers — as well as a household contact of the patient who developed respiratory symptoms but was never tested — actually developed H5N1 infection, it would suggest human-to-human transmission of the virus. Experts said that would be a major concern, because it would indicate an evolution of the virus.

“Even sporadic cases of human-to-human transmission indicate a big change in the virus and suggest it is exploring new directions in virus evolution that bring it closer to a pandemic virus,” James Lawler, MD, MPH, of the University of Nebraska Medical Center’s Global Center for Health Security, previously told MedPage Today.

Results of serology testing on the positive case and the household contact are still pending, CDC said in its update.

Missouri Department of Health and Senior Services has not identified ongoing transmission among close contacts of the case, according to CDC.